Touch panels that detect a touch of an indicator such as a finger and identify the coordinates of the touched position have conventionally been receiving attention as one of excellent interface means. Various types of such touch panels including the resistive film type and the capacitive type have been proposed and commercialized.
For example, a projected capacitive type touch panel disclosed in Patent Document 1 is known as one type of the capacitive type touch panels. These touch panels have advantages such as excellent fastness properties, the ability to detect touches of gloved fingers, and long lifetime because of the unnecessity of moving parts, and therefore various techniques have been proposed.
The touch panel disclosed in Patent Document 1 has a touch panel including detection row wiring (row detection electrodes) and detection column wiring (column detection electrodes), and calculates and outputs touch coordinates, which indicate the position touched by an indicator on the touch screen, on the basis of the result of detection of a touch capacitance made up of the electrostatic capacitances between each detection electrode and the indicator. Each detection electrode is formed of fine metal wiring having a zigzag pattern repeated in a zigzag manner. Electrodes using a transparent conductive film such as indium tin oxide (ITO) are increasingly used as such detection electrodes.
A case is assumed in which an operator actually provide an input with the touch of a finger on the touch screen by, for example, moving the fingertip to a position corresponding to a bottom-shaped display object. Since only uniform tactile sensation is obtained from the surface of the touch screen, which is an operation screen, the operator can hardly obtain tracking information other than visual information and needs to visually check the operation screen. Besides, in order to confirm whether the touch input has been accepted, it is necessary to check a response, such as switching of the display screen, from a device that incorporates the touch panel. In view of this, a function (tactile sensation feedback function) has been proposed, which is a function of, when an operator has touched the operation screen with an indicator such as a finger, returning a response involving some sort of tactile sensation such as vibrations or electrical stimulation to the indicator.
As one example of such devices for providing tactile sensation to fingertips that have touched the operation screen, a tactile stimulation generation device disclosed in Patent Document 2 is known. The tactile stimulation generation device includes a coordinate input device (touch screen) having a front surface provided with a tactile stimulation generation sheet, and provides electrical stimulation to the fingertips of the operator by passing current from the positive electrodes of tactile sensation generation electrodes installed on the tactile stimulation generation sheet toward the negative electrodes thereof through the fingertips.
Patent Document 3 discloses a tactile touch panel device having both a touch detection function and a tactile-voltage generating function. The tactile touch panel device is constituted by a combination of a substrate on which touch driving lines (excitation electrodes) are installed and a substrate on which touch sensing lines (detection electrodes) are installed. In a vertical blanking period when no image data is supplied, a tactile sensation generation voltage is applied to each of the touch driving lines and the touch sensing lines during periods when no touch has been detected. On the back side of the tactile touch panel, a shield layer is additionally provided to interrupt the application of tactile sensation generation signals having a tactile sensation generation voltage to the display panel. When the display panel is a liquid crystal display panel, the shield layer is formed on an opposite substrate or an array substrate.